Adds basic array methods RE: Issue GitbookIO#87

Adds methods.md file describing 4 basic array methods: Push, Pop, Shift and Unshift.

arrays/methods.md

@@ -0,0 +1,44 @@
+# Methods
+
+Arrays can be manipulated, searched, and modified using a number of <strong>Methods</strong> that are built in to the javascript language.
+  - A Method can be defined as a function that is stored in an object (Each javascript array is, in a deep technical sense, an object.)
+
+
+ADD & REMOVE <strong>LAST</strong> ELEMENTS FROM AN ARRAY
+
+- The PUSH method adds a new element to the end of any array.  What element? Whatever element you specify as the argument. ::smile::
+```javascript
+var array1 = [1, 2, 3];
+array1.push(4); 
+// RESULT: array = [1 , 2, 3, 4]; (The number 4 is PUSHED in)
+```
+
+- The POP method removes the last element of an array.  It does not require an argument.
+```javascript
+var array2 = [1, 2, 3, 4];
+array2.pop(); 
+// RESULT: array2 = [1 , 2, 3]; (The last item is POPPED off)
+```
+
+ADD & REMOVE <strong>FIRST</strong> ELEMENTS FROM AN ARRAY
+
+- The UNSHIFT method adds new elements sequentially to the start, or front of the array.
+```javascript
+var array3 = [0, 5, 10];
+array.unshift(-5); 
+// RESULT: array3 = [-5 , 0, 5, 10];
+```
+
+- The SHIFT method removes the first element of the array and, as if replacing a vacuum in space, SHIFTS all the other elements to the left.
+```javascript
+var array4 = [5, 6, 7, 8];
+array4.shift(); 
+// RESULT: array4 = [6, 7, 8];
+```
+
+*BONUS!: You can add more than one element at once, and they will be added sequentially.
+```javascript
+var array3 = [0, 5, 10]; 
+array3.unshift(-10, -5); 
+// RESULT: array3 = [-10, -5 , 0, 5, 10];
+```